Hi Rick ,
you have to install a perl distribution first. Perl is not included in vSphereCLI anymore.
I tested Active Perl . After the installtion of Active Perl i had to install an additional module :
ppm install XML-LibXML
If you have problems to execute a command try the complete path like this :
c:\perl64\bin\perl.exe esxcfg-mpath.pl --server esx01.lab.local --username root --password password -l
Good Luck